Michael Horton, Professor of Systematic Theology and Apologetics at Westminster Seminary California writes:
Whenever we gather for public worship, it is because we have been summoned. That is what “church” means: ekklesia, “called out.” …[Public worship] is a society of those who have been chosen, redeemed, called, justified, and are being sanctified until one day they will finally be glorified in heaven. We gather each Lord’s Day not merely out of habit, social custom, or felt needs but because God has chosen this weekly festival as a foretaste of the everlasting Sabbath day that will be enjoyed fully at the marriage supper of the Lamb. God has called us out of the world and into his marvelous light: That is why we gather.
(Taken from Michael Horton’s A Better Way, p.24)